Image-guided surgery (IGS) consists of real-time display of current location on X-ray images during surgery. Analogous to Global Positioning Systems, IGS systems provide intraoperative navigational information which has been shown to be particularly useful in complex cases such as those where anatomy has been distorted by disease and/or in "limited-access" surgery where small incisions are used. Systems are currently available for neurosurgery sinus surgery, and orthopedic surgery. In ear surgery (otologic surgery), the use of IGS systems has been limited by technical difficulties in achieving the sub-millimeter precision needed to avoid damaging adjacent structures. These difficulties relate both to fiducial marker placement and intraoperative registration. Fiducial markers are localizing devices on the patient which can be easily identified in X-ray images; the gold standard for fiducial markers is a rigid frame which is screwed directly into the patient's skull under local anesthesia. Registration involves identifying the fiducial markers on both the patient and the X-ray images and then linking or superimposing the X-ray image onto the patient; proper alignment of the X-ray images with the patient is critical and technologically difficult. The proposed study involves the use of a novel fiducial system that is non-invasive (it does not directly screw to the patient's skull but rather is secured in place by a mouth-guard/mouthpiece similar to those worn for sporting events) and non-obstructive (it does not impede the surgeon's movements). This fiducial system is couplet with a Vanderbilt-developed IGS system. As of this writing, the novel fiducial system and IGS system has been shown to achieve submillimeter accuracy when tested on locations within the ear of a human skull. The system will be tested on human beings undergoing elective ear surgery. Once safety has been documented, this system will be used for "computer-assisted" surgery where the desired surgery will be electronically drawn out on the X-ray and the surgeon's movements will be restricted from violating these plans without overriding the system. It is anticipated that this system will make ear surgery safer and more efficient.